Water Mimosa

Neptunia prostrata (Lam.) Baillon, Bull. Soc. Linn. Paris 1: 356. 1883.
Mimosa prosiraia l,a,m. ^ncycl. 1: 10. 1783. Neptunia oleracea Lour. Fl. Coch. 654. 1790. Mimosa laciisiris H. & B. PI. Aequin. 1: 55. 1806. Desmanthus lacustris Willd. Sp. PI. 4: 1044. 1806.
Floating in quiet water, glabrous throughout; stem stout, spongy, simple or little-branched, bearing large tufts of fibrous roots and hollow swellings 1-2 cm. in diameter. Stipules triangular-ovate, membranous, 5-7 mm. long; petioles 4-6 cm. long, glandless; pinnae 2 or 3 pairs, short-stalked; leaflets 8-20 pairs, linear or linear-oblong, 6-13 mm. long, obtuse or mucronulate, the venation obscure; peduncles axillary, solitary, in fruit 1.2-3 dm. long, bearing 1 or 2 ovate or lanceolate bracts; heads subglobose, many-flowered, the flowers white, fading yellow; perfect flowers with a calyx about 2 mm. long, the petals about 4 mm. long, the stamens about 8 mm. long; barren flowers basal, the calyx minute, the petals 2-4 mm. long, the linear staminodes 13-15 mm. long; legume oblong, mucronate, 2-2.5 cm. long, 8-10 mm. wide; seeds about 5 mm. long.
Type locality: India.
Distribution: Cuba; Jamaica; Yucatan. Tropical South America. Tropical Asia and Africa.